Hydrocarbon fuels from coal or any carbonaceous material



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man WH on. mzmmuom ...o uw. IIILIIII n 3G mm n kwh United States PatentO 3,477,942 HYDROCARBON FUELS FROM COAL OR ANY CARBONACEOUS MATERIALNeal P. Cochran, Frederick, Md., assigner to the United States ofAmerica as represented by the Secretary of the Interior Filed July 28,1967, Ser. No. 656,954 Int. Cl. Cg 1/06; C103 3/18; H01m 27/30 U.S. Cl.208-10 6 Claims ABSTRACT OF THE DISCLOSURE In the pyrolysis orhydrogasification of coal wherein the coal is converted to fluidproducts and hot solid char the improvement comprising passing a firstportion of char to a fuel cell or magneto-hydrodynamic device to produceD.C. current and passing a second portion of char to an internalresistant reactor wherein the char isreaeted with steam to form aproducer gas containing hydrogen using a portion of the D.C. currentproduced to control the heat input to the reactor.

This invention resulted-from work done by the Office of `Coal Researchof the Department of the Interior, and the domestic titleto theinvention is in the Government.

BACKGROUND OF INVENTION Field of invention This invention relates to thetreatment of coal `for the recovery of valuable hydrocarbon materials.More particularly, the invention concerns an arrangement whereby the hotchar from a coal pyrolysis or hydrogasication is used-to produce, incombination, electricity and producer gas containing hydrogen.

Description of the prior art The present invention comprises a new andimproved process for the conversion of coal into valuable volatllehydrocarbon fluids wherein said coal is treated to produce fluid'hydrocarbons and hot char and which a first portion of hot char isconverted into electricity and a second portion is contacted with steamin an electrogasication reactor. Alternately, all the hot char may becontacted with steam in the electrogasification reactor With a portion qof the gas being converted to electricity.

This process results in a uniquely efficient system requiring only coal,Water and air as inputs and which is susceptible to modificationswhereby a wide variety of valuable hydrocarbons may be produced.

Accordingly, the objects of this invention are:

t To provide a new and improved process for the treatment of coal.

To provide a method for producing valuable hydrocarbons from coal whichrequires inputs of only coal, air and water.

:To provide a method for efliciently using the char from a coalpyrolysis or gasification process, and to provide an improved coalconversion process which produces valuable volatile hydrocarbon fluidsand excess electricity.

ICC

Other features and advantages of the present invention will become clearon reading the following description wherein reference is made to theaccompanying drawings in which:

FIG. 1 represents a schematic flow diagram of a combined pyrolysis,power recovery, gasification and hydrogenation treatment of coaldesigned to recover a variety of valuable hydrocarbon fluids.

FIG. 2 schematically represents an internal flow diagram for a hightemperature fuel cell such as shown in FIG. l.

FIG. 3 schematically represents a combined hydrogasifcation,electrothermal gasification and power recovery process utilizing a hightemperature fuel cell, whereby coal is converted to valuable pipelinegas.

FIG. 4 schematically represents a process similar t0 that shown in FIG.3 -but using a lower temperature fuel cell.

FIG. 5 is a schematic flow diagram of a process similar to that shown inFIG. 1 except that the` power recovery portion of the process includes amagneto-hydrodynamic system.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. 1T there isshown a process for the production of a variety of valuable fuels fromcoal. In that figure, reference numeral 1 is a pulverized or finelydivided coal feed which if necessary is heated in a fluid bed at fromabout 60G-750 F. to prevent subsequent agglomeration. The size of thecoal should permit fluidization in bed 2 where the coal is treated atfrom about 800950 F. for a residence time of about 10 t0 60 minutes witha gas stream 3 consisting predominately of nitrogen. This treatmentresults in a dried and preheated lcoal stream 6 and an overhead l4 whichmay be either vented, or collected and condensed, or recycled as S tobed 2.

The predried coal stream 6 is led to a second fluidized bed 7, operatingin a range of from about 1l00-1200 F. There it is held for a residencetime of from l0 to 60 minutes so that pyrolysis occurs and volatiles 9are driven off as the predried feed 6 is contacted. with a hot gasstream 8.

A partially pyrolized eoal stream 10 is fed from uidized bed 7 tofluidized `bed 11 where it is contacted with a high temperature hydrogenstream 12 at about 1500 F. to 1600 F. again for a residence time of froml0 to 60 minutes. The volatiles driven off in this bed form stream 8which is sent back to bed 7.

A portion 14 of the char product from bed 11 is fed into uidized reactor1S where it is in contact with a steam input 16 at about 2500 F. toproduce a gas stream 17 comprising carbon monoxide and hydrogen. Reactor15 is of the internal resistance type, that is, the reactor is equippedwith electrodes across which an electrical potential is maintained. Whenthe reactor is fluidized with conductive char particles electric energyis supe plied and the temperature of the bed can be raised to a reactivelevel and a high degree of temperature control can be maintained.Reactors of this type are described in U.S. Patents 1,857,799;2,921,840; 2,968,683 and 2,978,315. Exiting reactor 15. stream 17 issent to a treatment at 18 where it is cleaned in a conventional mannersuch as by `condensing and separating to remove impurities, shifted withsteam to carbon dioxide and hydrogen and then passed through aconventional carbon dioxide ab sorber resulting in a stream 19consisting of carbon monoxide and of hydrogen. A portion of 19 is sentback as stream 12 to bed 11.

The remaining portion 20 of the char product from bed 11 serves as theinput to a high temperature fuel cell 21 which operates in the range offrom about 1000 C. to

3 1100 C. In this cell, which is described in Office of Coal ResearchReport No. 17 entitled, Review and Evaluation of Project Fuel Cell, char20 and air 21a are in the inputs and a nitrogen containing gas 22, power23, spent gas 24 and ash 25 are the outputs, Clean gas 26 is recycled aswell as a partially spent gas 27.

The operation of this high temperature cell will be more fullyunderstood as reference is made to FIG. 2.

There, char 20 is fed to reactor 28 where it is contacted with a gasAmixture 27 com-prising carbon monoxide, hydrogen, carbon dioxide andwater vapor such that the concentrations of carbon monoxide and hydrogenare about equal to the concentrations of carbon dioxide and water vaporrespectively.

The reaction of gas 27 with the char reduces the concentration of CO2and H2O and increases the concentration of CO and H2 forming a clean gasstream 26. Ash 25 resulting from this reaction may be discarded or sentto a mineral recovery (not shown). Stream 26 is fed to the fuelelectrode 29 of a first cell bank 30. In this cell, oxygen from airstream 21a takes on two electrons and enters the electrolyte as an ionleaving a deficiency of electrons on the air electrode 31 giving thatelectrode a positive charge. The oxygen ions then pass through theelectrolyte and combine with the incoming CO to form CO2 and theincoming H2 to form H2O there'by depositing two electrons on the fuelelectrode 29, When connected, in circuit, electrons iiow from the fuelelectrode 29 to the air electrode 31 giving a power output at 23. Anoxygen depleted air stream 22 consisting predominantly of nitrogen iswithdrawn from the air side, and a partially spent fuel stream 27 iswithdrawn from the fuel electrode side of the cell. A rst -portion ofthe latter is recycled to the reactor where the CO and H2 content isincreased and a second portion forms the feed to the fuel electrode 32of a second cell bank 33. As with the first cell bank, air 21 is fed tothe air electrode 34 causing current to flow from electrode 32 toelectrode 34. Nitrogen 22 is withdrawn from the air side and a spent gas35 rich in CO2 and H2O is withdrawn from the fuel side.

Returning now to FIG. 1 the refining of hydrocarbons takes places asvolatiles 9 from hed 7 are sent to an oil recovery 36 where they undergocondensation and separation by a water quench. Depending upon thecondition of the stream at that point, it may also be subjected to anacid treatment, an alkali treatment, or both. Following such treatmentsthe petroleum extract may be sent via 47 to a refining stage or via 37to a hydrocracking unit 38 where it is contacted with hydrogencontaining stream 39. Depending upon the extent of cracking and the useof other conversion processes such as reforming, hydrogenation,isomerization, etc., a variety of products can be recovered. Gaseousproducts exit via 44 and are sent to a gas recovery unit 45 where theyundergo clean-up condensation and if necessary separation into propaneand butane fractions by distillation. Other recoverable products includenumber 6 oil, 40, number 2, oil, 41, JP-S fuel, 42, and gasoline, 43.

Alternatively, hydrogen and carbon monoxide from stream 19 may bediverted to form methane or methanol. To produce methane at 50, thecarbon monoxide and hydrogen in stream 48 are. contacted at elevatedtemperatures over a methanation catalyst such as Raney nickel in a tubewall reactor 49 causing the following reaction If a methanol product 52is desired, the gases in line 48 are passed over a conventionalhydrogenation catalyst in a reactor 51 causing the following reaction tooccur:

CO-l-ZHW CH3OH Of course, the concentrations of carbon monoxide andhydrogen in stream 48 should be adjusted to provide optimum proportionsfor the methanation or hydrogenation processes.

When large amounts of methane or methanol are desired, the product fromoil recovery 36 will generally be sent to a refinery as crude via 47unless some alternative source of hydrogen is available for refiningpurposes.

A hydrogasification process according to the present invention isdescribed in FIG.'3- There, coal 100 which if necessary has undergone aheating treatment to reduce caking and prevent agglomeration, isintroduced into a hydrogasification unit 101 of the type described inOfiice of Coal Research Report entitled Process Designand Cost Estimatefor Production of 265 Million s.c.f./ day of Pipeline Gas by theHydrogasification of Biturninous Coa This unit is countercurrent,solids-downow reactor having an upper free-fall devolatization zone 102operating at from about 900-1300 F. at about 1000 to 2000 p.s.i.a. and alower moving tbed Zone 103 where the char from the upper zone iscontacted with upwardly directed'streams of hydrogen 104 and steam 105at a'reaction temperature of about 1700 F. The hydrogen reacts with thecarbon to form methane, and the steam reacts with carbon and carbonmonoxide to form hydrogen and carbon oxides. The ratio of moles HZ/molessteam shoul be approximately 1. i

^ The volatile products exit via 106 and any entrained fines areseparated in a cyclone 107 and returned through 108 to section 103. J

The volatiles pass through cyclone 107 and line 109 to a cleanup andmethanation process 110 of the type previously described. This processresults in a discard stream 111 of carbon dioxide, hydrogen sulfide andwater vapor and a product pipeline gas 112 having an energy value ofabout 940 B.t.u./s.c.f. The char produced in the hydrogasifier is splitinto two streams 113 and 114. The former is introduced in an internalresistance reactor 115 where it is contacted with steam 116 to form amixture of carbon oxides, hydrogen, water vapor and some hydrogensulfide. This mixture is led via 117 to a conventional clean-up at 118where carbon dioxide, water vaporl and hydrogen sulfide are removed andvented through line 119. The cleaned portion 120 consisting essentiallyof hydrogen goes to a water gas shift reactor 121 where it is contactedwith steam 122. The product of that reaction 123 comprises a mixture ofhydrogen, water vapor and carbon dioxide which is passed to a furtherclean-up at 124 where the carbon dioxide and water vapor 125 are removedleaving a gas consisting essentially of hydrogen. A portion of thishydrogen 104 furnishes the feed to hydrogasier 101. Excess hydrogen 126and the remaining portion of char 114 from the hydrogasier comprise thefuel feeds to a high temperature fuel cell unit 127 of the typepreviously described with reference to FIG. 2. The reaction of thesefuels with air 128 produces an intermediate recycle stream 129comprising hydrogen, carlbon monoxide, carbon dioxide and water vapor;ash 130; an oxygen depleted gas consisting primarily of nitrogen 131,power 132, and an off-gas 133 consisting mainly of water vapor andcarbon dioxide .but containing some carbon monoxide and hydrogen. v

This olf-gas may be recycled to clean-up 118 to conserve the hydrogenand carbon vmonoxide content, whereas the D.C. power 132 supplies'theelectrical energy requirements of reactor 115. Any excess power 133 maybe used to supply in-plant needs. l

-A similar system designed to produce pipeline gas is shown in FIG. 4.There, coal 200 which may be pretreated to prevent agglomeration isreacted in a hydrogasifier 201 of the type previously described, withincoming streams of hydrogen 202 and steam 203. The volatile productsexit the hydrogasifier through 204 and pass through'cyclone 205 wherelines are removed and sent back to the hydrogasifier via 205a. Thevolatiles are then processed at 206 for clean-up and lmethanation asdescribed with reference to FIG. 3 to produce an off-gas 207 containingcarbon dioxide, water vapor and hydrogen sulfide and a pipeline gas 208.l

The char produced in hydrogasier 201 is sent via line 209 to an internalresistance reactor 210 where it comes into contact with steam 211resulting in the formation of ash 212 and a high temperature hydrogenand carbon monoxide containing gas 213. Heat may be recovered from thisgas for internal process use. For example, FIG. 3 shows that it may beused to heat stea'm 203 in exchanger 214. Following this heat removalstep, the gas is purified at 215 by conventional means to removehydrogen sulfide, water vapor and carbon dioxide. The resultant stream 216 is divided such that a portion 217 flows through a turbine powergenerator unit `218 and then into a fuel cell 219. This type of cell hasin the past been called a high temperature cell but, for the purposes ofthis disclosure it will be termed a low temperature cell as itsoperating range 60G-700 C. is much lower than the solid electrolyte typefuel cell describe'd with reference to FIG. 2.

Fuel cell 219 is of the molten carbonate type familiar to the art. Cellsof this type are fully described in Hydrocarbon Fuel Cell Technologyedited by B. S. Baker, Academic-Press, 1965. A detailed flow plan of amolten carbonate fuel cell using a mixture of hydrogen and carbonmonoxide as a source of fuel, air as anoxidizer and water as a coolantis shown on page 275 of that publication. A simplified flow plan isdescribed in FIG. 4. Air 220 is fed to cell to react with the hydrogenand carbon monoxide feed 217. A portion of the fuel is oxidized to watervapor and carbon dioxide 222 which are removed from effluent 221 in aconventional purification stage 223. The remaining unoxidized fuel isrecycled to the cell via 224. Spent air is vented at 225 and the power232 produced in the cell furnishes the energy requirements for internalresistance reactor 210. Water 227 is used as a coolant for the cell andis thereby converted to high pressure steam 226. A portion 211 of thissteam is supplied to reactor 210 for reaction with char 209. A secondportion 226a may be recycled either to stream 203 or may be used as theinput to a water shift reactor.

A reactor of that type is shown as 228. A portion 229 of the hydrogenand carbon monoxide of stream 216 is used as a feed to the water shiftreactor along with steam 230. The product of the reaction is a stream231 consisting essentially of hydrogen which is purified at 232 toremove most of the water vapor and carbon dioxide which may be presentthus forming a product of substantially pure hydrogen 202 which is usedas the input to a hydrogasier 201.

Referring now to FIG. S there is shown a process similar to thatdescribed with reference to FIG. 1 but wherein there is employed a MHDdevice for converting char from the coal pyrolysis into electricalenergy for internal process use.

In this process coal 300, treated if necessary to prevent agglomeration,is fed as in FIG. l to a three stage pyrolysis. In the rst stage 301coal 300 is contacted with a continuously recycled gas stream 302 forabout to 60 minutes at a temperature in the range of about 60G-750 F.The heated coal 303 then enters the second stage 304 where it is broughtinto contact at 1100- 1200 F. for a residence time of from about 10 to60 minutes with a hot gas stream 305. This contact results in theliberation of volatiles 306 which are processed as in FIG. l at an oilrecovery 307, a hydrocracking unit 308 and a gas recovery and processingunit 309 to recover methane 350 and liquid products 360. The hot solids310 from stage 304 pass to the third stage 311 where they are reactedwith hydrogen at 1500-1600 F. from about 10 to 60 minutes. The gases305- resulting from this contact provide the input to the second reactor304 while the hot solid char is divided into streams 312 and 313.Portion 312 enters internal resistance reactor 314 wherein it is broughtinto contact with high pressure steam 315 to form hydrogen containinggas 316. This gas is shifted to form additional hydrogen and cleaned upto remove 46 carbon dioxide, hydrogen sulfide and water vapor at 317.The resultant hydrogen stream 318 is divided into two streams 319 and320. The former comprises the gas feed for the third stage 311 of thepyrolysis stages whereas the latter is directed to unit 308.

Char 313 is combusted with air 321 and an ionization promoter 338 suchas sodium, potassium or cessium in burner 322 and ash 323 is withdrawn..The remaining products of combustion 324 pass through amagnetohydrodynamic device 325 where power 326 is produced. Devices ofthis type which operate either as a Faraday generator oraccording to theHall effect are known in the art. The MHD unit used in the presentinvention may, for example, be of the type described by Rosa in U.S.Patent 3,182,213, designed to produce D.C. power. Other types mayhowever be used as, for example, that disclosed by Brill in U.S. Patent3,189,768 designed to produce A.C. power.

The hot gases 327 from the MHD device pass through heat exchangers 328and 329 where they are exchanged with a compressed air stream 330 in therst instance to form heated air 321 for burner 322 and water 331 in thesecond instance to form high pressure steam 332. A portion 315 of steam332 may provide the feed to reactor 314 while the remainder is fed to aturbine 333 driving a compressor 334 which compresses an air stream 335.The condensate 336 from turbine 333 can be recycled to provide water forheat exchanger 329.

After gases 327 have been cooled in heat exchangers 328 and 329, theyare fed to a clean-up and recovery unit 337 in which the promoter 338 isrecovered and recycled to burner 322 and a cooled ue gas 339 is vented.

A portion 340 of the power 326 produced in the MHD device is provided toreactor 314 to satisfy the energy requirements of the steam-carbonreaction, while the remaining portion 341 is applied to either forin-plant or commercial use.

Thus while preferred embodiments of the invention have been described,it is to be understood that various other embodiments wherein variousknown processes may be applied to the hydrocarbons recovered to formother valuable products are also contemplated.

What is claimed is:

1. In a process wherein coal is contacted with a hydrogen containing gasat high temperatures whereby said coal is converted into valuablehydrocarbon fluids and solid char the improvement comprising (a) passinga rst portion of said char to an internal resistance reactor zone;

(b) contacting said first portion of char in said internal resistancereactor zone with steam;

(c) passing a second portion of said char to a second reactor zone;

(d) oxidizing said second portion of char in said second reactor zone toform gaseous combustion products;

(e) passing said gaseous combustion products through a zone whereinelectrical energy is produced directly from said gaseous combustionproducts; and

(f) passing a portion of said electrical energy produced in step (e) tosaid internal resistance reactor zone of step (a).

2. The process of claim 1 wherein a hydrogen containing gas is recoveredfrom said internal resistance reactor zone and a portion of saidhydrogen containin gas is brought into contact with said coal.

3. The process of claim 2 wherein a portion of said hydrogen containinggas is brought into contact with a portion of said valuable hydrocarbonuids. l

4. The process of claim 1 wherein said electrical energy is produced ina high temperature fuel cell zone.

5. The process of claim 1 wherein said electrical energy is produced ina magneto-hydrodynamic zone.

7 y 6. 'In a process wherein coal is contacted with a hydrogencontaining gas whereby said coal is converted into valuable hydrocarbonuids and solid char the improvement comprising (a) passing said solidchar to an internal resistance reactor-,zone wherein it is treated withsteam to form a hydrogen containing gas;

(b) contacting said coal with a rst portion of said hydrogen containinggas;

(c) passing a second portion of said hydrogen containing gas to a lowtemperature fuel cell zone wherein it is oxidized thereby producingelectrical energy; and

(d) passing a portion of said electrical energy produced in step (c) tosaid internal resistance reactor zone of step (a).

8 References Cited UNITED STATES PATENTS OTHER REFERENCES B. S. Baker,Editor, Hydrocarbon Fuel Cell Technology, Academic Press, 1965, p. 275.

DELBERT E. GANTZ, Primary Examiner V. OKEEFE, Assistant Examiner U.S.Cl. X.R. 13 6-86

